1. Field of the Invention
The present invention relates to a wrist watch which contains an internal (electric) tag which is used for a RFID (Radio Frequency Identification) technique, to a radio watch of a wrist watch type which corrects the time instant by receiving a predetermined radio signal containing time instant information, and to an antenna which is used in these wrist watches.
2. Background Art
In the past, as a means for recognizing a person or object visually, a plate or the like has been provided bearing voter identification or a name or the like; but, with regard to the information which can be displayed upon such a plate, the scope thereof is extremely limited. Due to this, in recent years, an electric tag has been proposed which uses RFID (Radio Frequency Identification) technology and which is endowed with an electronic identification function. This tag for identification comprises an IC chip and an antenna which is electrically connected to this IC chip, and, if this tag for identification is attached to the above described plate, in addition to being able to validate information which is printed upon the surface of the plate, it is also possible to store various types of information in the above described IC chip. For example, it is possible to fit the above described plate with an attached tag to a person or to an object, and automatically to read out the information which has been stored in the IC chip, so as thereby to perform exit and entrance control for the person or object, or to perform stock management.
In recent years, this type of tag for identification is used as an identification device for controlling entrance through a gate which leads to a lift embarkment area for a ski area or to some type of recreational facility, or as a ticket or a season pass for a train or bus system. If the tag is used as identification for passing through this type of ski lift gate or for embarking in a transport device such as a train or a bus, the passenger who wishes to use the lift or the client who wishes to utilize the recreational facility, and particularly the passenger who wishes to embark in the transport device, is able to confirm that he is the proper person who is authorized to use this identification tag, simply by the operation of approaching the tag close to an identification means which is provided at the gate.
On the other hand, the person who wishes to use the ski lift or the recreational facility, or the passenger who wishes to ride in the transport device, normally wears upon his wrist a wrist watch which displays the time. Due to this, attempts have been made to include a tag for identification in such a wrist watch. If a tag for identification is housed in a wrist watch, it is not necessary for the person concerned to carry the tag for identification and the wrist watch separately and independently, and it is expected that this field of application will become more widespread than in the past, since the user can put the tag for identification on to his wrist without any sense that it does not belong there.
A per se conventional wrist watch, as shown in FIG. 32, comprises: a watch case 2 which comprises a ring shaped case 2a, a glass lid 2b which seals the front side of this ring shaped case 2a, and a rear lid 2c which seals the rear side of the ring shaped case 2a; a drive section 3 which is housed in this watch case 2; and a display section 4 which is housed in the watch case 2 and is driven by the drive section 3 to display the current instant of time. This wrist watch 1 is manufactured by first sealing the front side of the ring shaped case 2a by the glass lid 2b, then housing the display section 4 and the drive section 3 in that order within the interior of the ring shaped case 2a, and finally sealing the rear side of the ring shaped case 2a by affixing the rear lid 2c. Accordingly, when housing a tag for identification in a prior art type wrist watch 1, this is performed by winding the coil which is to be the antenna for the RFID tag so as to surround the periphery of the drive section 3 where there is a comparatively great amount of vacant space for clearance, in other words, so as to follow around the inner surface of the ring shaped case 2a and surround the drive section 3. An antenna which consists of a coil like this has an axis of magnetization which is perpendicular with respect to the face plate, so that it can be anticipated that, due to the axis of magnetization being perpendicular to the face plate which has the greatest surface area, the sensitivity of the RFID tag when using the wrist watch as an identification device will be enhanced, which will imply that the distance from an identification means at which it can be operated will be great.
However, in order for a conventional wrist watch to be durable and to project a feeling of high quality, the ring shaped case which constitutes its watch case is typically made from metal, which has a high electrical conductivity. Due to this, when such an antenna which consists of a coil wound to follow the inner surface of the case member is housed in this wrist watch, and when this antenna is receiving radio waves, induced electrical currents flow in the case member as well, and the problem arises that these induced currents tend to cancel out the radio waves from the outside. Furthermore as well, when electrical currents flow through the coil which constitutes the antenna, the problem arises that the sensitivity of the antenna can be deteriorated to a remarkable extent due to the flow of electrical currents in the metallic case member, and the consequence is that the distance from an identification means at which the RFID tag can be operated is remarkably shortened. In order to resolve this problem, it has been considered to form the case member of the watch case of the wrist watch from a non electrically conductive resin, but, if the case member is thus formed of resin, it is not possible for the wrist watch to project a really high quality feeling, and also there is the problem that its durability is deteriorated.
An objective of the present invention is to provide a wrist watch with an internal tag, which can house an RFID tag while maintaining the sensitivity of that tag comparatively high, and moreover without sacrificing the durability of the watch or the high quality feeling which it projects.
On the other hand, there is a per se conventional type of radio watch in which, as shown in FIG. 34, a rod shaped antenna 6 is provided on the external surface of a case 2 which is composed of a ring shaped case 2a, a glass lid 2b, and a rear lid 2c (see FIG. 33), with this antenna 6 being covered over by a cover 8 which is made of plastic or some other non magnetic material. With such a radio watch 1, the antenna 6 typically comprises a magnetic core member 6a which is made from a ferrite rod, and a coil 6b which is wound upon this magnetic core member 6a. Furthermore, two pairs of mounting arms 2d, 2d are fixed to the ring shaped case portion 2a so as to project therefrom on opposite sides thereof, and each of the ends of a wrist band 9 is pivotably fitted to one of these pairs of mounting arms 2d, 2d. By forming the antenna 6 of small diameter and short length, a compact size can be anticipated for the radio watch 1 constituted as described above. However, with the above described prior art type radio watch, there is the problem that there is a substantial deterioration of its external appearance, because the central line of the band 9 and the central axis of the circular case 2 do not coincide with each other.
Moreover, there is another type of wrist watch style radio watch which, as shown in FIG. 33, comprises a watch case 2, a drive section 3 which is housed in this watch case 2, a display section 4 which is housed in the watch case 2 and is driven by the drive section 3 to display the current instant of time, and a controller 7 which controls the drive section 3 based upon the detection output of an antenna 6 which is housed in the case 2. This wrist watch 1 is manufactured by first sealing the front side of a ring shaped case 2a by a glass lid 2b, then housing the display section 4 and the drive section 3 in that order within the interior of the ring shaped case 2a, and finally sealing the rear side of the ring shaped case 2a by affixing a rear lid 2c. Accordingly, in such a prior art type wrist watch 1, a comparatively great amount of vacant space is available for clearance around the periphery of the drive section 3, and, if the antenna 6 can be housed between the inner surface of the ring shaped case 2a and the drive section 3, it becomes possible to make the central line of the band 9 and the central axis of the case 2 to coincide with each other, and accordingly it can be anticipated that the beauty of the external appearance of this radio wrist watch 1 can be enhanced, because it can be made to have an external appearance which is similar to that of a conventional wrist watch.
However, in order for a conventional wrist watch to have durability and projects a high quality feeling, the ring shaped case and the rear lid which are incorporated in its watch case are made from metal, which has high electrical conductivity and is endowed with the characteristic of intercepting radio waves. Due to this, if the antenna is simply just housed in the space between the inner surface of the ring shaped case and the drive section, the problem arises that, since the ring shaped case and the rear lid constitute a barrier to the passage of radio waves, accordingly the antenna cannot receive the radio signals of the specific frequency (40 kHz) containing time instant information.
Furthermore, even if the radio waves are able to pass through the ring shaped case and the rear lid, if an antenna is used which has a coil which is wound so as to surround the drive section and follow around the inner surface of the ring shaped case so that its axis of magnetization is perpendicular to the face plate of the watch, when the antenna is receiving radio waves, induced electrical currents flow in the ring shaped case and in the periphery of the rear lid, so that the problem arises of serious deterioration in the sensitivity of the antenna. In order to avoid this problem, it has been considered to form the ring shaped case and the rear lid of the watch case of the wrist watch from a non electrically conductive resin, but, if the ring shaped case and the rear lid are thus formed from resin, the wrist watch cannot project a really high quality feeling, and also the problem arises that its durability is deteriorated.
Another objective of the present invention is to provide a radio watch which, while not losing any of its high quality feeling or beauty of external appearance, contains an antenna which is capable of accurately receiving a radio signal containing time instant information.
Furthermore, with such a watch, it has been considered to house both an antenna for receiving prescribed radio signals which contain time instant information and also an antenna which constitutes an identification tag, between the inner surface of the ring shaped case 2a and the drive section 3, both said antennas being provided separately and independently. However, with a prior art type watch, this necessitates enlargement of the space between the inner surface of the ring shaped case 2a and the drive section 3, and as a result there is the inconvenience that the outer diameter of the wrist watch as a whole is increased. Furthermore, housing these two antennas in the watch case means that it becomes necessary to set up these two antennas separately, and the problem arises that the unit cost of the wrist watch is increased because of the number of manufacturing operations for housing these two antennas in the watch case. In addition, when thus housing the two separate antennas, if these antennas have magnetic core members, the magnetic flux bundle due to one antenna exerts a reaction upon the other antenna, and the problem arises that both of these antennas may not receive their appropriate radio signals properly.
Furthermore, there are some types of conventional wrist watch in which only the ring shaped case is made from metal, with the rear lid being made from a plastic. With such a wrist watch, even though the radio waves can pass through the rear lid because it is made from plastic, nevertheless, induced electrical currents still flow in the ring shaped case when the antenna is receiving radio waves, and these induced currents tend to cancel out the radio waves from the outside, which remarkably deteriorates the sensitivity of the antenna. In order to resolve this problem, it has been considered to form the ring shaped case of the watch case of the wrist watch from a non electrically conductive resin as well, but, if both the ring shaped case and also the rear lid of the wrist watch are formed from a resin, it becomes a wrist watch of the same general level as a comparatively low cost wrist watch of the toy type, and it is impossible for it to project the really high quality feeling of a conventional wrist watch.
Another objective of the present invention is to provide an antenna for use in a wrist watch, which can receive both a radio signal for reading out information which is stored in an IC chip, and also a radio signal which contains time instant information. A further objective of the present invention is to provide a wrist watch which, while not losing any of its high quality feeling or beauty of external appearance, contains an antenna which can reliably receive a radio signal which contains time instant information and also a radio signal for reading out information which is stored in an IC chip.